Karl Rove said Tuesday that Mitt Romney is "close to a decision" on a running mate and predicted that the announcement will come next week, "but it could come as early as Friday."

"We could get one on Friday because they've got a bus tour announced for four days in key battleground states that starts on Saturday," he said on Fox News. "My gut tells me though that it's more likely to come next week. I think Romney is going to spend this bus tour laying out his -- the grass-roots plan that he laid out last week, called the 'Plan for the Middle Class.' I think he's going to try to give that some depth and substance."

He added: "But who knows? I think he's close to a decision. He is clearly being very serious in his approach to this. My gut tells me that it's going to come a little bit later than this week, but it could come as early as Friday."

Rove declined to predict who will be selected as the vice presidential nominee, noting his failure to predict past nominees Joe Biden, Sarah Palin, Joe Lieberman and Dick Cheney.

Rove also blasted a TV ad by Obama super PAC Priorities USA Action in which a former employee of a Bain Capital-owned steel plant links his wife's cancer death to Romney and Bain's decision to close the plant, causing the employee's family to lose health care.

"Yeah, I think it's dumb," Rove said of the ad. "What they're basically trying to say is -- this is sort of the Hail Mary pass, this is when people in campaigns get desperate and go over the top."

He later added: "[Priorities USA senior strategists] Bill Burton and Paul Begala may think they're really smart by running this ad. They may be patting themselves on the back, but this is the kind of ad that blows up in the face of the candidate who they're trying to help, and in this instance it's so over the top and so mean and so, you know, off target that it's going to hurt Obama and his reputation more than it's going to hurt Romney."